You're talking about the dogbone insert, not the engine/trans mounts. Specifically, 034's early revision was prone to cracking and bending (mine cracked). I'm not sure how they fare today, but I don't recommend those types of inserts for stage 2 and beyond... I'd recommend a full pendulum mount like HPA's.
I slapped on the 034 engine/trans mounts in Jan or Feb and they've been fantastic! I noticed literally zero added NVH on top of what was already there from the HPA dogbone (which is little). They clean up the slop nicely, very pleased with them as well with my HPA dogbone, like someone else posted. Wheelhop 95% eliminated for me on lowering springs, when I added coils my wheelhop was gone completely.
They've been through several track days and autocrosses this year as well, they're holding up just fine. Again, very happy with them. We'll see how they hold up to BOSS600 power in the coming weeks.